This invention relates to copolyetherimides, and more particularly to a new genus of copolyetherimides characterized by such advantageous properties as good ductility, good melt flow properties and high heat resistance.
Polyetherimides are a well-known class of commercially available polymers having excellent chemical resistance, high temperature stability and electrical and mechanical properties. An important subgenus of polyetherimides comprises polymers prepared by the reaction of diamines such as m-phenylenediamine with dianhydrides such as the dianhydride of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]-propane. As disclosed, for example, in U.S. Pat. No. 5,229,482, such polyetherimides may also be prepared by the reaction, typically in the presence of a phase transfer catalyst, of a bisphenol alkali metal salt with a bis(chlorophthalimide) such as 1,3-bis[N-(4-chlorophthalimido)benzene]. The latter method has gained favor in recent years by reason of its relative simplicity (e.g., a minimum number of steps) and high yield.
Various properties of polyetherimides could benefit from improvement. They include melt flow; heat resistance, which is related to heat distortion temperature; and ductility, which can be measured by temperature at which the transition from the brittle to the ductile state occurs.